1. Field
The following description relates to a communication system including receiving antennas and a time tracking method thereof.
2. Description of Related Art
Wireless sensor network is gaining popularity with the rapid growth and commercialization of a wireless network technology. Also, wireless technology standards for exchanging data in wireless sensor networks are defined by the Institute of Electrical and Electronics Engineers (IEEE), for example, Bluetooth®, IEEE standard 802.15.4 (2011), ZigBee®, and other similar standards.
A wireless sensor device has a wide range of applications including home security, medical field, mobile healthcare, chemical and biological abnormality monitoring, machine abnormality and breakdown diagnosis, environment monitoring, disaster-related information sensing, intelligent transportation management, real-time security, and remote surveillance.
Sensors in wireless sensor networks and near field communication sensors need to be small in size, and require low power and low complexity to be able to operate a large number of sensors for an extended period of time.
Specially, strict requirements of low complexity and low power exist for a wireless body area network (WBAN) in which wireless communication is established between a sensor installed in a body and a nearby mobile device or another sensor installed in another body.
To attain low complexity and low power, there is a need to introduce an ultra-low power radio frequency (RF) structure rather than a conventional high power RF structure; however, an ultra-low power analog circuit, which is normally used in WBAN, degrades performance.